The present invention relates to a golf club head having a hollow construction.
Recently, large golf club heads having a head volume exceeding 430 cc have been developed. Since the large head has an enlarged sweet area on the head, it has become possible to manufacture an easy-to-use golf club that is less likely to cause a decrease in carry even in an off-center shot. However, if a head having a hollow construction is made large, the thicknesses of members forming a crown part and a sole part must be decreased. Therefore, a ball hitting sound at the time a ball hits tends to be low.
Generally, a high ball hitting sound peculiar to a metal head is to the golfer's liking. Therefore, various ways and means have been devised to control the ball hitting sound of such a large-size and light-weight head. For example, Japanese Patent Application Publication No. 2003-339922 describes a technique in which, to produce a high and clear ball hitting sound, a metallic thin small piece is fixed on the inner surface of a golf club head on the toe side of a sole part in a state in which one plate surface of the small piece adheres closely to the sole part. Also, Japanese Patent Application Publication No. 2006-204604 describes a technique in which, to improve the low ball hitting sound, at least one rib extending from the toe side to the heel side is arranged in the sole part, and this rib is extended curvedly so that the toe-side end and the heel-side end of the rib are nearer to the face side than the central area of the rib.
On the other hand, not all golfers like a metallic and high-pitched sound. Japanese Patent Application Publication No. 2008-200319 and Japanese Patent Application Publication No. 2008-200339 describe a technique in which, to make the ball hitting sound of golf club head loud and to make the reverberation long, the radius of curvature of the sole part, crown part, or side part is made larger than the minimum radius of curvature of the face surface of golf club head, and a rib or a flat plate shaped member is provided in a portion having a larger radius of curvature so that the value of resonance frequency of this portion is within ±10% of the value of resonance frequency of the face surface.